Migrate authc dependency from security plugin to core security service (

#187124)

## Summary

Part of #186574

Background: This PR is an example of a plugin migrating away from
depending on the Security plugin, which is a high-priority effort for
the last release before 9.0. The Cases plugin uses authc.getCurrentUser
from the security plugin's start contract on the server side.

This PR migrates authc.getCurrentUser from the security plugin start
contract to the core security service.

Checklist
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/cases/server/client/factory.test.ts

@@ -52,7 +52,7 @@ describe('CasesClientFactory', () => {
       });
 
       expect(args.securityPluginStart.userProfiles.getCurrent).toHaveBeenCalled();
-      expect(args.securityPluginStart.authc.getCurrentUser).not.toHaveBeenCalled();
+      expect(args.securityServiceStart.authc.getCurrentUser).not.toHaveBeenCalled();
       expect(createCasesClientMocked.mock.calls[0][0].user).toEqual({
         username: 'my_user',
         full_name: 'My user',
@@ -63,7 +63,7 @@ describe('CasesClientFactory', () => {
     it('constructs the user info from the authc service if the user profile is not available', async () => {
       const scopedClusterClient = coreStart.elasticsearch.client.asScoped(request).asCurrentUser;
       // @ts-expect-error: not all fields are needed
-      args.securityPluginStart.authc.getCurrentUser.mockReturnValueOnce({
+      args.securityServiceStart.authc.getCurrentUser.mockReturnValueOnce({
         username: 'my_user_2',
         full_name: 'My user 2',
         email: 'elastic2@elastic.co',
@@ -76,7 +76,7 @@ describe('CasesClientFactory', () => {
       });
 
       expect(args.securityPluginStart.userProfiles.getCurrent).toHaveBeenCalled();
-      expect(args.securityPluginStart.authc.getCurrentUser).toHaveBeenCalled();
+      expect(args.securityServiceStart.authc.getCurrentUser).toHaveBeenCalled();
       expect(createCasesClientMocked.mock.calls[0][0].user).toEqual({
         username: 'my_user_2',
         full_name: 'My user 2',
@@ -95,7 +95,7 @@ describe('CasesClientFactory', () => {
       });
 
       expect(args.securityPluginStart.userProfiles.getCurrent).toHaveBeenCalled();
-      expect(args.securityPluginStart.authc.getCurrentUser).toHaveBeenCalled();
+      expect(args.securityServiceStart.authc.getCurrentUser).toHaveBeenCalled();
       expect(createCasesClientMocked.mock.calls[0][0].user).toEqual({
         username: 'elastic/kibana',
         full_name: null,
@@ -113,7 +113,7 @@ describe('CasesClientFactory', () => {
       });
 
       expect(args.securityPluginStart.userProfiles.getCurrent).toHaveBeenCalled();
-      expect(args.securityPluginStart.authc.getCurrentUser).toHaveBeenCalled();
+      expect(args.securityServiceStart.authc.getCurrentUser).toHaveBeenCalled();
       expect(createCasesClientMocked.mock.calls[0][0].user).toEqual({
         username: null,
         full_name: null,

x-pack/plugins/cases/server/client/factory.ts

@@ -12,6 +12,7 @@ import type {
   ElasticsearchClient,
   SavedObjectsClientContract,
   IBasePath,
+  SecurityServiceStart,
 } from '@kbn/core/server';
 import type { ISavedObjectsSerializer } from '@kbn/core-saved-objects-server';
 import { SECURITY_EXTENSION_ID } from '@kbn/core-saved-objects-server';
@@ -57,6 +58,7 @@ import { EmailNotificationService } from '../services/notifications/email_notifi
 interface CasesClientFactoryArgs {
   securityPluginSetup: SecurityPluginSetup;
   securityPluginStart: SecurityPluginStart;
+  securityServiceStart: SecurityServiceStart;
   spacesPluginStart?: SpacesPluginStart;
   featuresPluginStart: FeaturesPluginStart;
   actionsPluginStart: ActionsPluginStart;
@@ -257,6 +259,7 @@ export class CasesClientFactory {
 
     try {
       const userProfile = await this.options.securityPluginStart.userProfiles.getCurrent({
+        // todo: Access userProfiles from core's UserProfileService contract
         request,
       });
 
@@ -273,7 +276,7 @@ export class CasesClientFactory {
     }
 
     try {
-      const user = this.options.securityPluginStart.authc.getCurrentUser(request);
+      const user = this.options.securityServiceStart.authc.getCurrentUser(request);
 
       if (user != null) {
         return {

x-pack/plugins/cases/server/client/mocks.ts

@@ -6,7 +6,11 @@
  */
 
 import type { PublicContract, PublicMethodsOf } from '@kbn/utility-types';
-import { loggingSystemMock, savedObjectsClientMock } from '@kbn/core/server/mocks';
+import {
+  loggingSystemMock,
+  savedObjectsClientMock,
+  securityServiceMock,
+} from '@kbn/core/server/mocks';
 import type { ISavedObjectsSerializer } from '@kbn/core-saved-objects-server';
 
 import {
@@ -226,6 +230,7 @@ export const createCasesClientFactoryMockArgs = () => {
   return {
     securityPluginSetup: securityMock.createSetup(),
     securityPluginStart: securityMock.createStart(),
+    securityServiceStart: securityServiceMock.createStart(),
     spacesPluginStart: spacesMock.createStart(),
     featuresPluginStart: featuresPluginMock.createSetup(),
     actionsPluginStart: actionsMock.createStart(),

x-pack/plugins/cases/server/plugin.ts

@@ -186,6 +186,7 @@ export class CasePlugin
       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       securityPluginSetup: this.securityPluginSetup!,
       securityPluginStart: plugins.security,
+      securityServiceStart: core.security,
       spacesPluginStart: plugins.spaces,
       featuresPluginStart: plugins.features,
       actionsPluginStart: plugins.actions,

x-pack/plugins/cases/server/services/notifications/email_notification_service.ts

@@ -100,7 +100,7 @@ export class EmailNotificationService implements NotificationService {
       );
 
       const uids = new Set(assignees.map((assignee) => assignee.uid));
-      const userProfiles = await this.security.userProfiles.bulkGet({ uids });
+      const userProfiles = await this.security.userProfiles.bulkGet({ uids }); // todo: access userProfiles from core security service start contract
       const users = userProfiles.map((profile) => profile.user);
 
       const to = users

x-pack/plugins/cases/server/services/user_profiles/index.ts

@@ -27,7 +27,7 @@ const MIN_PROFILES_SIZE = 0;
 
 interface UserProfileOptions {
   securityPluginSetup: SecurityPluginSetup;
-  securityPluginStart: SecurityPluginStart;
+  securityPluginStart: SecurityPluginStart; // TODO: Use core's UserProfileService
   spaces?: SpacesPluginStart;
   licensingPluginStart: LicensingPluginStart;
 }
@@ -58,6 +58,7 @@ export class UserProfileService {
     size?: number;
     owners: string[];
   }) {
+    // TODO: Use core's UserProfileService
     return securityPluginStart.userProfiles.suggest({
       name: searchTerm,
       size,